TABLE 6 1965 Requirements for Doctors in Thirty-One LDC's and in U.S.A. as Percent of 1955 Number of Doctors Change in Doctors Population Growth 1955-65 per 100,000 Population 1955-65 Zero Actual LDC's Zero (remains 17.9) 0 25.6 +3.3 (increases to 21.1) 18.5 49.5 U.S.A. Zero (remains 130) 0 17.0 +18 (increases to 148) 14.4 33.5 Source: (21). growth and zero increase in ratio, since insufficient data are available from the LDC's on replacements needed for death, retirement, and migration, although the actual number in 1965 presumably includes them. For the LDC's, instead of the 18.5 percent increase in numbers of doctors (33,584) required to move from 17.9 to 21.2 doctors per 100,000 population had no population growth occurred, 49.5 percent was actually required (25.6 percent or 46,611 doctors to maintain the 1955 ratio as population grew and 23.8 percent or 43,360 doctors to increase the ratio for the new population). For the United States, instead of the 14.4 percent increase in numbers of doctors (29,867) required to move from 130 to 148 doctors per 100,000 population had no population growth occurred, 33.5 percent was actually required (17 percent of 35,316 doctors to maintain the 1955 ratio as population grew and 16.5 percent or 34,335 doctors to increase the ratio for the new population). Population Growth and Health Services in the Next 20 Years The clearest relationship between population growth and personal health services in the LDC's during the next 20 years is the direct demand more population creates for more health services. This direct effect will be considered here in several ways. One is the requirement to maintain the current level of service under conditions of probable-compared to zero-population growth. This is the familiar measure of how fast one must run to stay in the same place. Another is the requirement to achieve a planned or desired levelrcent over the 1955 level. Three countries had increases in their ratio of physicians to population by over 100 percent of the 1955 level, four by over 50 percent, and seventeen by less than 50 percent; seven had no change or decreases up to 44 percent. The average increase in doctors per 100,000 population was 3.3. With two exceptions (U.A.R. and Korea), this change by individual country was less then 10 per 100,000 and in nineteen was less then 5. Most of the decreases were in newly independent African countries. For the same time period, the increase in ratio of physicians to population for the United States was 14.4 percent of the 1955 level or 18 doctors per 100,000 population.